To first order, we can estimate the temperature increase timescale assuming triple-\(\alpha \)  burning is the dominant nucleosynthetic energy source [1]}. Assuming the shell parameters from [2]} and a 100% energy to temperature conversion, we find that the temperature of a \(q=0.7\)  merger with initial T\(_{\rm {He,init}} = 1.5\times 10^{8}\)  K doubles within the first few years after merger. This time reduces to a few days for \(q=0.6\)  (T\(_{\rm {He,init}}=2\times 10^8\)  K) and a few minutes for \(q=0.5\)  (T\(_{\rm {He,init}}=3\times 10^8\)  K). The shell-burning temperatures for \(q<0.6\)  mergers can thus exceed \(4\times 10^{8}\)  K. RCB stars would then be consistent with low mass-ratio (\(q<0.6\) ) mergers and dLHdC stars would be consistent with higher mass-ratio mergers (\(q>0.7\) ) Note that for mergers where T\(_{\rm {He}}>4.5\times 10^{8}\)  K, other elemental abundances predicted by models do not agree with the observed RCB abundances [3]}. This suggests that there is a lower limit on the mass-ratios of white dwarf binaries that can produce RCB/dLHdC stars.. More detailed studies of nucleosynthetic energy production are required to determine the exact ranges of q that might form RCB and dLHdC stars
